Bsurfaces addon not working correctly
I just tested the Bsurfaces addon (version 1.5) with blender version 2.75a and it is completely functional (with a bug that disables Global Undo).

However there are a few things you need to be sure of to get it to work.


Set the grease pencil source to Object (this is your problem)

The tool tip even says that it is needed for Bsurfaces to work.

For best results draw the strokes in Object mode.
However if you drew in edit mode and it looks like this:

You can click on the Enable Editing button in the Grease Pencil tab of the tool shelf.
Or you can click the Edit Strokes button. It is in the Tools tab of the tool shelf.

I prefer the latter because you can simple delete the bad points, and not bother with trying to reposition them.
Save often, as in before you start Bsurfaces and after you create every piece you are happy with. You will still find bugs.




Last I would refer you to my answer on resources for Bsurfaces, there is a great PDF, that is still very useful.